Pharmaceutics · 2011 · 37 citations · 13 references
PharmacyPharmaceuticsPharmacologyBioavailabilityDrug DeliveryTransdermal Drug DeliveryBioavailability EnhancementMicroneedle-based DeliveryPermeation EnhancersPhysical Enhancement TechniquesSkin Barrier FunctionVitamin B12 DeficiencyAnodal IontophoresisChemical Permeation EnhancersMicroneedlesPhysical Penetration EnhancementStratum Corneum Barrier ModulationStratum Corneum PermeabilityTransdermal Delivery SystemsTransdermal Drug Delivery Systems
Vitamin B12 deficiency, which may result in anemia and nerve damage if left untreated, is currently treated by administration of cyanocobalamin via oral or intramuscular routes. However, these routes are associated with absorption and compliance issues which have prompted us to investigate skin as an alternative site of administration. Delivery through skin, however, is restricted to small and moderately lipophilic molecules due to the outermost barrier, the stratum corneum (SC). In this study, we have investigated the effect of different enhancement techniques, chemical enhancers (ethanol, oleic acid, propylene glycol), iontophoresis (anodal iontophoresis) and microneedles (soluble maltose microneedles), which may overcome this barrier and improve cyanocobalamin delivery. Studies with different chemical enhancer formulations indicated that ethanol and oleic acid decreased the lag time while propylene glycol based formulations increased the lag time. The formulation with ethanol (50%), oleic acid (10%) and propylene glycol (40%) showed the maximum improvement in delivery. Iontophoresis and microneedle treatments resulted in enhanced permeation levels compared to passive controls. These enhancement approaches can be explored further to develop alternative treatment regimens.
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Crystalline Vitamin B <sub>12</sub>
Edward L. Rickes, Norman G. Brink, Frank R. Koniuszy et al. · Science · 1948 · 547 citations
Purification of Anti-pernicious Anæmia Factors from Liver
E. Lester Smith · Nature · 1948 · 241 citations